MSISDN stands for Mobile Station International Subscriber Directory Number. In 3GPP/LTE network, each mobile subscriber will be having a unique MSISDN number. This number is mainly used for routing calls to the subscriber.

Use case

• XYZ Telecom, an internet service provider needs to track subscriber activity based on log messages. In most countries it is a requirement from law enforcement agencies to have NAT logs with MSISDN numbers to identify and track subscriber activity over Internet.

MSISDN is the primary key for uniquely identifying a subscriber in UMTS/GSM network. It is telephone number to a SIM card in a Mobile phone. When XYZ Telecom, deploys NetScaler in their environment, LSN module in NetScaler logs MSISDN number of subscribers for tracking the subscriber activity.

Instructions

How to enable MSISDN logging in NetScaler using Configuration Utility

Step 1:  Navigate to  Configuration tab -> System -> Large Scale NAT -> Profiles

Step 2: Under Profile click on Logging Tab -> Add

Step 3:    Under Profile Name mention the name of the profile to be created and under Subscriber ID, select “ENABLED” to enable MSISDN to be logged from the LSN session.

Step 4: After the profile is created, it should be bound to an LSN group.
Configuration tab -> System -> Large Scale NAT -> Groups -> Select the group to which the LSN profile should be bound -> click edit

Step 5: Under logging profiles, select the Logging profile to be used by the LSN group and bind it to the  

How to enable MSISDN logging in NetScaler using Command Prompt?

To add LSN log profile with Subscriber ID logging:
>add lsn logprofile <logprofilename> [-logSubscriberID ( ENABLED |
       DISABLED

To edit LSN log profile with Subscriber ID logging:
> set lsn logprofile <logprofilename> [-logSubscriberID ( ENABLED |
       DISABLED )]

To remove LSN log profile with Subscriber ID logging:
>rm lsn logprofile <logprofilename>
To bind/unbind LSN log profile to LSN group:
>bind lsn group <groupName> -logProfile <logProfileName>
>unbind lsn group <groupName> -logProfile <logProfileName>

Subscriber ID logging will log many parameters, along with MSISDN. A typical log will have time stamp, Client IP, NAT IP, Dest IP, Protocol type etc.
Example: Oct 14 15:37:22 <Source IP> 10/14/2015:10:08:14 GMT  0-PPE-6 : default LSN LSN_SESSION 25012 0 :  SESSION DELETED E164:9876543210 Client IP:Port:TD <Client IP>:4649:0, NatIP:NatPort <NAT IP>:45195, Destination IP:Port:TD <Dest IP>:0:0, Protocol: ICMP
 
If MSISDN is not available at NetScaler for a session, then the logging field for MSISDN will be left blank.